Process of manufacturing cyanid of hydrogen.



IGNACY moscIoKI .AND' QASIMIR JABLczYnsKI, or rnmsune, swrrznnnann, AS-

.sIGN'oBs I zunrcn, SWITZERLAND.

TO THE.1 ?IRM F ALUMINUM-INDUSTRIE-AKTIEN-GESELLSCHAFT, 0F

rnoonss or MANUFACTURING CYANID or HYDROGEN.

oa ers.

No Drawing.

' To all whom it may concern as it known that we, IGNAGY Moscioiti and CASlMni JABLCZYNSKI, sub ects ot the Czar of Russia, and residing at Freiburg,

Switzerland, have invented a certain new and useful Improved Process of Manufacturing Uyanid of Hydrogen, of which the following is a specification.

This invention relates to improvements in processes of manufacturing hydrogen cyanid; and an object of this invention is to provide a process which will give a greatly increased "yield of hydrogen cyanid as compared with processes heretofore known and which will, therefore, result in a reduced cost of production of hydrogen cyanid.

The synthesis of cyanid of hydrogen from nitrogen, carbureted hydrogen and hydrogen is known, owing to the work of Berthelot. At first he electrically heated a mixture of nitrogen and carbureted hydrogen, but obtained no result because the whole of athe carbon set free by the decomposition of the hydrocarbon separated in the form of soot. Only by adding such a quantity of hydrogen to the aseous mixture that the proportion of t e hydrocarbons in it amounted to only approximately 10% was it possible for him to prevent the separation of carbon and to produce cyanid of hydrogen. In this process, however, the output of cyanid of hydrogen is so small that it is not adapted for the industrial manufacture of cyariid of hydrogen. Now we have, found by'experiment that in the synthesis of cyanid ofhydrogen from a mixture of a hydrocarbon, nitrogen and hydro en the output increases with an increase in the percentage of nitrogen in the mixture the proportion of hydrocarbon remaining the same-and that the dilution of the hydrocarbon with hydrogen instead of with nitrogen greatly reducies the output and preferably isedected to only such an extent as a pears absolutely requisite for revehting t e separation of carbon. Ad itional experiments have shown us that when employing more or less saturated hydrocarbons (which come into consideration principally for economical reasonsir there results in addition to the synthesisof cyanid of hydrogen a decomposition of these hydrocarbons in the sense fiipecification of Letters Patent.

Patented Jan. 21,1913.

Application filed July 7, 1910. Serial No. 570,778.

that hydrocarbons poorer in hydrogen are produced and elemental hydrogen is liberated. For economically carrying the process into practice it is necessary to subject the gaseous mixture again to the same process after the constituents of the mixture have been caused to react by great heat and after the mixture has been freed from the cyanid of hydrogen formed thereby. But if this is allowed to take place without the exercise of precautionary measures, the gaseous mixture will. gradually become diluted with hydrogen and the'output will decrease considerably in consequence of the diminished concentration of the nitrogen in the gaseous mixture.

Now a primary object of the process according to this invention is to prevent this result and to maintain the required high proportion of free nitrogen in the repeatedly-used gaseous mixture, While keepin therein an amount of hydrogen just su ficient to prevent deposition of soot due to separation of carbon. To this end, the prejudicially acting surplusage of hydrogen is regularly removed from the constantly-cin mixture the high degree of concentration of.

the nitrogen which Is necessary to obtain ghe high yield of hydrogen'cyanid sought We may remove the excess hydrogen from the gaseous mixture according to the followi'ng methods:

(a) The mixture of hydrogen, nitrogen and hydrocarbon is subjected to difiusion. Each gas then diffuses at an equal partial pressure with a velocity which is inversely. proportional to the square root of its density. Therefore a gas which for the most part consists of hydrogen can be removed from the gaseous mixture.

(7)) The hydrogen is oxidized by catalysis, the reaction being limited to the hydrogen. Hair be used as oxidizing agent,

nitrogenis simultaneously supplied to the ing again supplied to'the gaseous mixture by employing air as the oxidizing agent. The quantity of air supplied to the gaseous mixture is exactly sutiicient to burn the excess of hydrogen contained in the mixture,

which excess amounts to a few per cent.

that the reduction of the mixture is caused only by the hydrogen. This process may, by way of example, be carried out indeed so that the gaseous mixture is conducted rather rapidly over copperoxid at a faint red heat.

' Since the gaseous mixture contains hydrogen in large excess over the hydrocarbon, the part of the hydrogen to be gotten rid of in this way will burn; on the contrary, none of the hydrocarbon or only an infinitesimally small portion thereof will burn. Our process may, however, also be carried into practice, for example, by preliminarily heating the gaseous mixture consisting of nitrogen, hydrogen and hydrocarbon and then highly heating it electrically to a very high temperature. The hot gaseous mixture is then cooled and the cyanid of hydrogen which is formed is removed in a suitable manner. The surplus hydrogen is withdrawn by dividing, the current of gas into two unequal parts. The larger part is supplied again to the reaction chamber, whereas the smaller part is supplied to a place where its energy is otherwise utilized, '6. g. thermically. Instead of this separated part a corresponding mixture of nitrogen and hydrocarbon is supplied to the gaseous mixture flowing to the reaction chamber. In this manner we control the concentration of hydrogen in the gaseous mixture which passes into the electric flame, so that it never exceeds a certain limit and the high degree of concentration of the free nitrogen required for the best results and highest yield of hydrogen cyanid is constantly maintained. Further, care is also exercised that other gases (6. 9. carbon monoxid, argon, etc.,) which are prejudicial to the desired reaction and which constantly pass into the gaseous mixture for various reasons, do not accumumoved from the gaseous mixture subjected.

to the cycle of operations, the degree of concentratio'n of the working or effective constituents of the gas mixture will be diminished and in this way the yield will also be reduced. The quantity of gas mixed with the freshly supplied gases, is then preliminarily heated and highly electrically heated again.

Instead of pure nitrogen, air may be present in the fresh supply 'of gas which to the gaseous mixture undergoing the reaction is added as a substitute for the gases which are drawn off and for those which are bound by the reaction. Since, after the division of the gaseous mixture, the larger part of the same which continues to circulate always contains an excess of hydrogen in proportion tothe oxygen contained in the freshly-supplied air, the latter can burn the hydrogen to water without practically disturbing the reaction. The employment of air has, therefore, the advantage that a larger part of the hydrogen contained in the gaseous mixture is removed than when pure nitrogen is employed. Consequently, there can be a corresponding reduction in the amount of hydrocarbon which must after the electrical heating be removed from the circulating gaseous mixture in order to prevent the accumulation of hydrogen and to maintain in that way the necessary high degree of concentration of the nitrogen.

The following is given as a specific ex ample of the carrying out of our new process: The initial or basic substance taken is a gas made from oil and having the following approximate composition:

Methane 50.3% Heavy hydrocarbons (for example,

acetylene, ethylene, propylene, benzene) 22. 5% Hydrogen"; 23. 2% Nitrogem; 4;. 0%

drogen thus set'free unite with the nitrogen to form hydrogen cyanid. The part of the gas which does not pass through the body of the flame, which is, therefore, subjected to no high heating and, hence, which is also. not decomposed nuxes with the highly-heated gas coming from the flame and serves to chill the latter gas. This chilling is necessary, since the hydrogen cyanid formed and contained in the highly-heated gas would again itself be decomposed; that is to say,

the reaction which took place in the flame would be rendered of no effect. Since now as just stated, a decomposition of the hydrocarbon takes place in only that art of the gas which passes into the body 0 the flame, the furnace leaves the'other art of the gas unchanged. In order, there ore, to be able to carry on the process economically, the gas, after the replenishment of the ingredients used up in the formation of the hydrogen cyanid, will again be conducted through the furnace; that is, the process is carried on in a recurring cycle of opera tions. Now there goes on along with the above-described decomposition of the hydrocarbon into carbon and hydrogen still another decomposition, namely, in this way, that the completel or almost completely saturated hydrocar ons (as, for exam le, methane, ethylene), by separation of hy rogen, change into unsaturated hydrocarbons (as, for example acetylene). In this connection there will therefore be surplus free hydrogen, (that is, hydrogen not combined to form hydrogen cyanid) which in working in a cycle would, if precautions were not taken, accumulate soon to such an amount that the required high degree of concentration of the free nitrogen would be destroyed and that, according to the chemical law of action of substances, the yield of hydrogen cyanid would be diminished below a mini mum which would no longer be profitable for an industrial use of the process. Hence, this surplushydrogen which is newly produced in connection with each passage of the gas through the flame-arc, mustevery time before or after the separation of the produced hydrogen cyanid be removed. This removal is accomplished according to one of the methods set forth in the foregoing description. The separation of the hydrogen cyanid from the gaseous mixture can be so effected, for example, that the same is led into a solution of caustic potash or caustic soda, which will with the hydrogen cyanid form, respectively, potassium cyanid and sodium cyanid. After the separation of the hydrogen cyanid and the removal of the surplusage of hydrogen, hydrocarbon and also nitrogen (so far as the addition of the latter has not already been accomplished in connection with the removal of the hydrogen) will be supplied to the gaseous mixture according to the consumption of these ingredients which results from the reaction in the arc of flame, whereupon the entire process begins anew.

Suitable a paratuses for the carrying out of the herelnbefore-described process are shown and described in detail in United States Letters Patent Nos. 930,212 and Having now particularly described and.

ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

l. A step in the process of synthetically manufacturing cyanid of'hydrogen from a repeatedly-used gaseous mixture containing nitrogen, hydrogen and hydrocarbon, comprising keeping up the strength of the gas eous mixture in nitrogen and preventing the dilution of the same with hydrogen by re-. moving therefrom "the surplus hydrogen which is evolved durin the reaction.

2. A process of synthetically manufacturing cyanid of hydrogen from a gaseous mixture containing nitrogen, hydrogen and hydrocar bon, comprising highly heating the gaseous mixture and subsequently cooling the same; removing therefrom cyanid of hydrogen; keeping up the strength of the gaseous mixture in nitrogen and preventing the dilution thereof with hydrogen by removing the surplus hydro-gen which is evolved during the reaction; again highly heating the residual gaseous mixture and subsequently cooling the same; removing cyanid of hydrogen; removing the surplus hydrogen which is evolved during the reaction; and repeating the operations.

3. A process of synthetically manufacturing cyanid of hydrogen from a gaseous mixture containing nitrogen, hydrogen and hydrocarbon, comprising highly heating the gaseous mixture and subsequently cooling the same; removing therefrom cyanid of hydrogen; keeping up the strength of the gaseous mixture in nitrogen and preventing the dilution thereof with hydrogen by removing the surplus hydrogen which is evolved during the reaction; supplying to the residual gaseous mixture hydrocarbon and'a gas of which free nitrogen is a constituent; highly heating the gaseous mixture thus formed and subsequently cooling the same; removing cyanid of hydrogen. therefrom; and repeating the operations.

4. A process of synthetically manufac-- turing cyanid of hydrogen from a gaseous mixture containing nitrogen, hydrogen and hydrocarbon, comprising highly heating the gaseous mixture and subsequently cooling the same; removing therefrom cyamd of hydrogen; keeping up the strength of the gaseous mixture in nitrogen and preventing the dilution thereof with hydrogen by removing the surplus hydrogen which is evolved during the reaction; supplying to the residual gaseous mixture air and a hydrocarbon; highly heating the gaseous mixture thus formed and subsequently cooling the same; removing cyanid of hydrogen therefrom; and repeating the operations.

5. A process of manufacturing hydrogen cyanid comprising heating a gaseous mixture containing nitrogen, hydrogen and hydrocarbon; cooling the mixture; removing therefrom the cyanid of hydrogen formed; dividing the residue into parts; mixing with one of these parts hydrocarbon and a gas of which free nitrogen is a constituent; and

subjecting the mixture last formed to the same steps as theoriginal gaseous mixturewas subjected to.

6; A process of manufacturing hydrogen cyanid comprising highly heating a gaseous mixture containing nitrogen, hydrogen and hydrocarbon; cooling the mixture; removing therefrom the hydrogen cyanid formed; dividing the residue into parts; mixing with one of these parts air and hydrocarbon; and

subjecting the mixture last formed to the same steps as the original gaseous mixture was subjected-to.

In testimony whereof, we aflix our signatures in the presence of two witnesses.

IGNACY MOSCICKI. GASIMIR J ABLGZYN SK I. Witnesses FRIEDRICH NARzsLr, FRIEDRICH LU'rz. 

